1. Field of the Invention
The present invention relates to a method of mounting an IC chip on a substrate and an apparatus manufactured by the method, and more particularly to a flip chip mounting method and a semiconductor apparatus formed thereby.
2. Description of Related Art
In a typical conventional flip chip mounting method, a sheet of anisotropic conductive adhesive or a film of anisotropic conductive adhesive (herein after referred to as ACF) 4 shown in FIG. 3, or anisotropic conductive adhesive paste-like (herein after referred to as ACP) 9 shown in FIG. 4 is placed between an IC chip 1 and a substrate 5. Then, the IC chip 1 and the substrate 5 are electrically and mechanically bonded to each other by heat pressure bonding.
Also, as shown in FIG. 5, a molding material 6 is used to adhere an IC chip 1 to a substrate 5. The IC chip 1 has electrode pads formed on the surface of the IC chip and bumps 2 formed on the electrode pads, and the substrate 5 has a metal pattern formed on the surface of the substrate 5. Electrical conduction between the IC chip and the substrate is obtained by using eutectic crystallization between the bumps 2 and the metal on the surface of the substrate 5. It is noted that a sheet of anisotropic conductive adhesive (ACF) is likewise called as an anisotropic conductive film or an anisotropic conductive sheet.
In the conventional technique, a sheet of anisotropic conductive adhesive (ACF) or anisotropic paste-like adhesive (ACP) is independently used, as described above. For example, poor bonding may occur because the ACF may not be sufficiently bonded in an area of the connecting surface, or bubbles 7 generated during the heat pressure bonding process may remain along the connecting surface of the IC chip, as shown in FIG. 3. Further, in the case of an ACP, electrical and mechanical bonding capability of the ACP may not be sufficient. The conventional technique therefore does not provide a high level of stable and reliable mounting method.
Also, when the metal eutectic reaction between bumps on the IC chip and metal on the substrate surface is used, good quality eutectic metal is not formed and poor bonding takes place if there is even a small defect in the finishing of the bumps or the metal surface.